Gas filling apparatus for lamp manufacture



Dec. 23, 1941. RAM. GARDNER 5 GAS FILLING APPARATUS FOR LAMP MANUFACTURE Filed. May 18, 1940 v 21 P "W 2 Q 2 mi;-

L9a 20 1,17 W////// //////Al h\\\ l; 2; 18 I L I v 3 Rom/Va /1 64mm Patented Dec. 23, 1941 MANUFACT URE Roland M. Gardner, Swampscott, Mass., assignor to Hygrade Sylvania.Corporation, a corporation of Massachusetts Application May 18, 1940, Serial No. 335,979 (c1. ire-2) 3 Claims. This invention relates to an exhausting machine for electric gaseous discharge lamps, and

more particularly to a device for controlling the' pressure of the gases used in the exhausting process.

An object of the invention is to provide a means for securing a correct pressure of gas in the lamp when it isready to be sealed-off, after having been exhausted.

Another object is to provide a means for constantly securing an exact pressure of gas in the lamp after it has been exhausted.

The regulation of the pressure by a petcock or some similar device controlled by hand has proven to be undesirable because many times. inaccuracies creep in due to the human element involved. In my invention the pressure is mechan- I ically controlled.

Other objects and advantages of the present invention will be apparent from the drawing and description thereof in which:

Figure 1 is a view of the gauge, showing its relationship to those parts of the exhausting machine with which it is connected.

Figure 2 is a cross section view of the two positions on the machine which pertain to my invention. I In my invention, when the lamp has been sumciently exhausted and is ready to be filled with gas, it is filled to some pressure greater than the desired pressure. The excess is then pumped oil through the gauge described below, and the lamp is sealed oiT containing gas under the desired pressure.

In Figure 1, the gauge consists of two envelopes, I and 2, of difierent diameters, one inside the other. In my invention, these envelopes are made of glass, but they may be made of metal or some other substance. on the side of the inner envelope, at a position relatively close-to the bottom, there are one or more small vents, 3, inserted therein. In the bottom of the outer or larger envelope, there is a quantity of a liquid with an extremely low vapor pressure, for example n-butyl-phthalate l. The height 01' this liquid, with an extremely low. vapor pressure is determined by a considerationof two factors; one is the position, in respect to height, at which the small vent or vents, 3, appear on the side of the inner envelope, and the other is the amount of pressure which is desired in the lamp.

Figure 2 is a cross-section view of the two heads 9 23 on the exhausting machine which must be considered in a. description of my invention. This viewshows the two metal plates, I1 and I8, the

connecting lines I3 and I4 and the lamps I5 and I6. Plate II is stationary but plate I8 moves with the indexing of the machine.

In a rotary exhausting machine, such for exissued January 31, 1939, to G. A. Espersen, when a lamp has been flushed and exhausted, the machine indexes to a position where the lamp may be filled with gas. In Figure 2, this position is reached when the lamp I5 reaches aposition where it establishes a. connection with the line I4. This line I4 leads-to a cylinder 22 or some other container in which the gas to be used is stored. If, for example, two mm. of mercury pressure is the desired pressure, between four and ten mm. may be introduced. Whenthe lamp has been filled with gas to an excessive pressure, the machine indexes and the lamp moves to a position corresponding to the position of lamp I6 as shown in Figure 2. The pressure of gas in the lamp is maintained during the indexing movement by means of an oil seal between the plates I1 and I8. 7

When the lamp reaches the position assumed by lamp I6 in Figure 2, it is in contact with the line I2 leading to the gauge in my invention. This line I2 in Figure 2 is an extension of line I2 in Figure 1. When the lamp reaches this posl- T tion, it contains a pressure of from 4 to 10 min.

of gas. The pressure in the line I2 at the time the lamp comes in contact with it is 2 mm. With this condition existing, the excess pressure of gas will force its way down through line I2 and into the inner envelope I of the gauge where it will come in contact with a height of n-butyl phthalate at the vent or vents, -3. Since 2 mm. or pressure is the desired pressure of gas to be permitted to remain in the lamp, a height of n-butyl.

phthalate, h, equivalent to 2 mm. of mercury is placed in the bottom of the outer envelope 2. Thus all pressure present in line I2, in excess of 2 mm. will bubble out through the 2 mm. of n-butyl phthalate and be drawn off by the vacuum pump 2| to which line II is connected.

To line I2, at a point just before the line enters the inner envelope I there is attached a monomof gas. If it contains a pressure somewhat in excess or this amount, the height of mercury i will be depressed and the height of mercury 20 will rise under the influence of this pressure.

when the mercury column 20 reaches a height 5 where contact is established with lead-in wire 19, the circuit becomes closed and the light 9 will glow, indicating the pressure condition to the operator, who may then open the petcock or valve 10 and allow the vacuum pump to pump out the 10 with air caused by a leaky lamp, for there would 15 always be at least 2 mm. of air in line 12 due to the height of n-butyl phthalate in the gauge.

What I claim is: 1. In an automatic gas-filling machine for lamps, a device regulating the gas pressure to be sealed into the lamp, said device comprising: a quantity of liquid having a low vapor pressure; an envelope forming a reservoir for said liquid;

an exhaust pump in communication with said envelope above the surface of said liquid; a tube extending into said liquid in said reservoir, said tube having at least onesmall vent below the surface of said liquid; a head for connection to lamps to be exhausted and filled; and means for placing said head in communication with said tube.

2. The combination of claim 1 in which the said liquid is n-butyl phthalate.

3. The combination of claim 1 and: a shunt path between the head and exhaust pump; and a valve for closing said path.

ROLAND M. GARDNER. 

